English as a Second Language/sentences

Question1. The police ascertained the identity of the criminal before arresting him.
The company ascertained its truth before publishing the news.

Are both sentences grammatically correct?
(1.) In the second, what is a substitute for “publishing”?

2. Our manager resigned last week and the new manager will assume the job next Tuesday.

When I ask you a question and you don’t respond, I assume that you don’t know.

Are both sentences grammatically correct?
(1.) In the first sentence, can I replace “assume” with “undertake” or “take on”?
(2.) In the second, can I say also, “When you don’t answer my question, I assume that you don't’ know”?

3. When I called you and nobody answered the phone, I assumed you were not at home.
When we decided to go camping, we assumed the weather would be nice today. Unfortunately, it has been raining all day.

Are all the sentences grammatically correct?

4. It is inhumane to perform experiments on animals for new drugs.
The R&D department carries out a series of experiments to test new products before a launch.

Are both sentences grammatically correct?
(1.) In the first sentence, can I say also, “It is inhumane to experiment new drugs on animals”

5. His research on AIDS contributed to a cure for the disease.

I will research on the Internet and in the library before I start the project.

Are both sentences grammatically correct?
(1.) In the second, can I say, “I will do research on the Internet and in the library..”?

6. I usually research different websites before I make an online purchase.
I research companies when I am looking for a job.

Are both sentences grammatically correct?
(1.) In the first sentence, can I say also, “..before I shop online”?
(2.) In the second, can I say also, “I do search on/about companies when…”?

Answer1. The police ascertained the identity of the criminal before arresting him.
The company ascertained its truth before publishing the news.

Are both sentences grammatically correct? yes
(1.) In the second, what is a substitute for “publishing”? broadcasting, disclosing

2. Our manager resigned last week and the new manager will assume the job next Tuesday.

When I ask you a question and you don’t respond, I assume that you don’t know.

Are both sentences grammatically correct? yes, the second is incomplete though "I assume that you don't know how to answer it"
(1.) In the first sentence, can I replace “assume” with “undertake” or “take on”? yes
(2.) In the second, can I say also, “When you don’t answer my question, I assume that you don't’ know”? yes but again "you don't know how/what to answer (it)"

3. When I called you and nobody answered the phone, I assumed you were not at home.
When we decided to go camping, we assumed the weather would be nice today. Unfortunately, it has been raining all day.

Are all the sentences grammatically correct? yes

4. It is inhumane to perform experiments on animals for new drugs.
The R&D department carries out a series of experiments to test new products before a launch.

Are both sentences grammatically correct? I'd rephrase the first
It's inhumane to test new drugs on animals.
(1.) In the first sentence, can I say also, “It is inhumane to experiment new drugs on animals” yes, much better; see my version above

5. His research on AIDS contributed to a cure for the disease.
I will research on the Internet and in the library before I start the project.

Are both sentences grammatically correct? yes
(1.) In the second, can I say, “I will do research on the Internet and in the library..”?
yes

6. I usually research different websites before I make an online purchase.
I research companies when I am looking for a job.

Are both sentences grammatically correct? yes

(1.) In the first sentence, can I say also, “..before I shop online”? yes
(2.) In the second, can I say also, “I do search on/about companies when…”? yes, the original is better though.